Countries that are not independent states are often called dependencies or territories as in “French Polynesia is a devolved parliamentary dependency”.
In the context in which I am using the word, it would be inappropriate to use the word “colonizer” to refer to the country of which the dependency is a territory. I'm thus looking for a word that captures the country that has territorial control over the dependency that is less politically charged. I do, of course, recognize that this is a politically charged subject but where I am using the term it must be as neutral as possible.
Ideally, the term should be one word and it should apply to both current dependencies and to former colonies. In a sense, it should be exactly like the word “colonizer”, but without the historical connotations.
Edit: Ideally, I'm looking for a single word. The way it would be used is to indicate the name of a dataset column, which indicates the name of the former colonizer for territories that have gained independence and the name of the country exercising control over the territory if the territory is not an independent state. An example of the former is the United Kingdom to Australia and an example of the latter is France to New Caledonia. Note, that I do not consider New Caledonia to be a colony of France (largely because a majority rejected independence in a referendum and extensive self-governance), although I do recognize that this is a contested classification.